A man who lives in a neighbouring street earlier told ABC he was woken by screaming and yelling about 1am.

"I just heard a lot of screaming and yelling and a bit of fighting, and the cops flew past here and headed up this way," Mr Shreck said.

"It was real loud yelling and screaming. It sounded pretty bad. It sounded like a man."

Mr Steel said while details were still emerging, he believed the incident would have a massive impact on the victims' families and the WA community.

"At this particular point in time there's a very complex, and I would say horrific crime scene in place, and it will take us some time to process that crime scene, and that could be days," he said.

"This is a terrible tragedy for the family involved, for their extended family and for those first responders who were forced to attend what was a horrific crime scene. My heartfelt condolences go out to all of those who have been affected by this tragedy."